Thank you for reaching out to Constant Contact API Developer Support. My team is here to assist outside software developers with questions about building into Constant Contact's API.
Currently there are not any Events endpoints available in the V3 API. As new endpoints become available for V3, they’ll be announced on the V3 API Release Notes page. Your feedback and experience with this request is essential to improving our product, so thank you for reaching out to us regarding this matter. We look forward to releasing new endpoints for V3 in the future to better meet our customers’ needs.
Constant Contact V3 API Release Notes